1. Field of the Invention
The present invention relates to an optical connector used in optical data transmission, more specifically, to an optical connector with shutter for opening and closing an insertion opening, to where a plug of an optical fiber cable is inserted, with a shutter.
2. Description of the Related Art
The optical connector used in optical data transmission has, on both a transmission side and a reception side, a basic configuration including a combination of a case having an insertion hole to where the plug of the optical fiber cable is inserted and an optical element arranged at the back of the insertion hole so as to optically couple with the plug inserted into the insertion hole of the case.
In such optical connector, in order to prevent foreign materials such as dust from entering the insertion hole when the plug of the optical fiber cable is not inserted, the opening of the insertion hole, that is, the insertion opening is closed with an opening/closing type shutter.
Generally, the shutter here has a single swinging type hinge configuration that pivots with one side edge as the center, more specifically, two types of out-swinging type that opens towards the outside of the case and an in-swinging type that opens towards the inside of the case are known. However, in a case of the out-swinging type, the operation of opening the shutter when plugging the plug becomes necessary. Even in a slide type shutter that slides in a direction orthogonal to the direction of the plug insertion, the operation of opening the shutter also similarly becomes necessary. On the other hand, in a case of the in-swinging type, the shutter is automatically opened with the plugging operation of the plug, and thus the overall evaluation including operationality is high for the in-swinging type.
The optical connecter equipped with in-swinging shutter is disclosed in for example, Japanese Laid-Open Patent Publication No. 2001-201663. The conventional configuration of the optical connector of this type is described with reference to FIG. 10.
The optical connector with shutter shown in FIG. 10 includes a receptacle case 2 including an insertion hole 1 to where the plug of the optical fiber is inserted, an optical element 3 arranged at the back of the insertion hole 1 so as to optically couple with the plug inserted into the insertion hole 1 of the case 2, and an in-swinging shutter 4 that is hinge supported near the opening of the insertion hole and that opens inward with the insertion of the plug into the insertion hole 1.
The shutter 4 closes the insertion opening by being elastically held at a closed position by a bias spring not shown. When the plug is inserted into the insertion hole 1 of the case 2 in this state, the shutter 4 is pushed inward by the plug thereby pivoting inward with the hinge shaft as the center as shown with an arrow, and is pivoted until finally reaching a state of lying along an internal wall surface of the case 2 and completely opening the opening of the insertion hole 1, that is, the insertion opening. When the plug is extracted from such state, the shutter 4 automatically returns to its original closed position with the extraction of the plug by the biasing force of the bias spring.
Such optical connector with shutter includes that complying with for example, MOST standard. The MOST standard is an abbreviation of Media Oriented System Transport standard, one form of LAN for automobiles, for supporting high-speed optical data link of in-vehicle multimedia equipment such as car navigation system or in-vehicle audio, various changers and the like, and is a registered trademark of OASIS.
In the connector complying with the MOST standard, a cylindrical projection 5 projecting from a hole-back side of the plug insertion hole 1 towards the opening side is arranged. The projection 5 is a plug holding part that is inserted to the distal end part of the plug to hold the plug inserted into the plug insertion hole 1, and is usually referred to as a ferrule receiver. The plug inserted to the plug insertion hole 1 is passed through the inside of the plug holding part 5 and optically coupled with the optical element 3 in the case.
However, in the optical connector complying with the MOST standard and provided with an in-swinging shutter, the interference with the plug holding part 5 referred to as the ferrule receiver of when the shutter 4 is opened inward becomes a problem. That is, the pivot of the shutter 4 is inhibited by the plug holding part 5. In order to solve such problem, the distal end part of the plug holding part 5 is cut diagonally in the optical connector of FIG. 10. Consequently, the interference of the shutter 4 and the plug holding part 5 is avoided, but the plug holding part 5 may not satisfy the dimensions defined in the standard.
As an optical connector that has a configuration in which the interference between the in-swinging shutter and the plug holding part is avoided and the plug holding part is provided with the dimensions as defined in the standard, that shown in FIG. 11 is known. In the optical connector with shutter shown in FIG. 11, a so-called double door configuration in which the shutter 4 is divided into two parts of a main shutter 6 and a sub shutter 7 in a direction orthogonal to the hinge shaft is used, and each shutter is hinge-coupled to the case 2 on the opposing side and is elastically held at the closed position by the respective bias spring. With such configuration, the interference between the shutter 4 and the plug holding part 5 is avoided and the dimensions defined in the standard can be provided to the plug holding part 5.
On the other hand, however, a separate shutter accommodating part 9 for accommodating the sub shutter 7 becomes necessary on the side opposite the original shutter accommodating section 8 for accommodating the main shutter 6, thereby increasing the outer dimensions of the optical connector.
Further, as the bias spring for elastically holding the in-swinging shutter in the closed position, normally, a torsion coil spring including a pair of arms projecting from the coil part in two directions is arranged between the back surface of the shutter and the internal wall surface of the case. More specifically, in a state the coil part is faced towards the opening side and in combination with the hinge shaft of the shutter, the torsion coil spring is arranged between the back surface of the shutter and the internal wall surface of the case.
In this case, in the assembly step of the optical connector, in particular, in the step of attaching the shutter to the case, the task of attaching the torsion coil spring to the shutter in advance, and attaching the shutter to the case while pushing the arm on the case side down towards the shutter side become necessary. However, in the conventional optical connector, since the torsion coil spring attached to the shutter is unstable and the arm easily tilts to the right or the left, the workability of attaching the shutter to the case is very bad. Further, when the arm is tilted to the left or the right, the spring load as planned in designing may not be ensured.